Surface Drill and Blasting: An Overview
Surface drill and blasting is a widely used method in mining, quarrying, and construction to break rock or other hard materials for excavation, mineral extraction, or site preparation. The process involves drilling holes into the rock surface, loading them with explosives, and detonating them to fragment the material.
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Key Steps in Surface Drill and Blasting:
1. Planning & Design
– Survey the site to determine rock type, geological conditions, and desired fragmentation size.
– Design the blast pattern (hole spacing, burden, depth) based on rock properties.
– Obtain necessary permits and ensure safety compliance.
2. Drilling
– Use rotary or percussion drills to create blast holes (typically 3–12 inches in diameter).
– Hole depth depends on excavation requirements (e.g., bench height in mining).
3. Explosive Loading
– Fill holes with explosives (ANFO, dynamite, emulsion explosives).
– Use detonators (electric or non-electric) and timing delays for controlled blasting.
4. Blast Initiation
– Safely detonate explosives in a sequence to optimize fragmentation and reduce vibration.
– Monitor ground vibration and airblast to comply with regulations.
5. Post-Blast Activities
– Inspect the muck pile for misfires.
– Remove fragmented material using loaders or excavators.
– Assess blast performance (fragmentation size, flyrock control).
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Equipment Used:
– Drilling Rigs: Rotary drills (for softer rock), DTH (Down-The-Hole) drills (for hard rock).
– Explosives: ANFO (Ammonium Nitrate Fuel Oil), emulsions, dynamite.
– Initiation Systems: Electric/non-electric detonators, delay relays.
– Safety Gear: Blasting mats, warning signs, seismographs.
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Advantages:
– Cost-effective for large-scale operations.
– Flexible in varying rock conditions.
– Allows precise control over fragmentation.
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Challenges:
– Safety risks (flyrock, misfires).
– Environmental concerns (noise, dust, vibrations).
– Regulatory restrictions near populated areas.
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Safety & Environmental Considerations:
– Follow strict protocols for handling explosives.
– Use blast mats or berms to contain flyrock.
– Monitor vibrations to prevent structural damage.
– Minimize dust and noise pollution